Preparation And Luminescent Properties Of Li（Na,K）Ba（Sr,Ca）B₉O₁₅:Eu³⁺,M(M=Gd³⁺,Zn²⁺) Phosphors

In this research,a series of Li（Na,K）Ba（Sr,Ca）B₉O₁₅:Eu³⁺,M(M=Gd³⁺,Zn²⁺)phosphors were synthesized by high temperature solid-state reaction method in air atmosphere.For the synthesized LiBaB₉O₁₅:Eu³⁺phosphors,the effects of calcination temperature,holding time,the excess amount of H₃BO₃ and Eu³⁺doping concentration on the crystal phase and luminescence properties were investigated.The results demonstrate that single-phase LiBaB₉O₁₅ is formed when sintered at 700°C for 1h.Phosphors with 15%excess of H₃BO₃ and Eu³⁺doping concentration 0.59 have the strongest luminescence intensity.The maximum excitation peak of samples is located at 394 nm,indicating that the prepared phosphors can be effectively excited by n-UV and exhibit a strong red emission of Eu³⁺at612 nm under the excitation of 394 nm wavelength.According to Dexter theory,the concentration quenching mechanism of Eu³⁺in LiBaB₉O₁₅ matrix is multipole interaction.The luminescence properties of the prepared LiBaB₉O₁₅:0.59Eu³⁺phosphor and the commercial Y₂O₃:Eu³⁺phosphor was compared.The emission intensity of LiBaB₉O₁₅:0.59Eu³⁺is weaker than that of Y₂O₃:Eu³⁺under excitation of 260 nm wavelength,stronger than the Y₂O₃:Eu³⁺under excitation of 362 nm and 394 nm wavelength.The CIE chromaticity coordinates of LiBaB₉O₁₅:0.59Eu³⁺phosphor（0.6415,0.3411）is closer to the standard red-light CIE coordinates（0.67,0.33）than commercial Y₂O₃:Eu³⁺phosphor（0.6186,0.3325）.Through the mutual substitution between alkali metals and alkaline earth metals in the LiBaB₉O₁₅,Li（Na,K）Ba（Sr,Ca）B₉O₁₅:Eu³⁺phosphors were synthesized by replacing Li⁺with K⁺and Na⁺,and replacing Ba²⁺with Sr²⁺and Ca²⁺,the effect of the change of the matrix composition on the luminescence properties of the phosphors was studied.The results show that the peak shape and peak position of the defferent matrix samples are almost the same,only the relative intensity of the peak has changed significantly,and the phosphor with Li Sr B₉O₁₅ as the matrix has the strongest emission intensity.For the synthesized Li Sr B₉O₁₅:Eu³⁺phosphor,the effect of calcination temperature,holding time and Eu³⁺doping concentration on the crystal phase and luminescence properties were investigated.The results show that the crystallinity of the samples is good when the calcination temperature is 750°C and the holding time is 1 h-5 h.When the Eu³⁺doping concentration is 0.52,the phosphor Li Sr B₉O₁₅:Eu³⁺has the strongest luminescence intensity.The relative intensity ratio R of the emission peak at 611 nm（⁵D₀→⁷F₂）and 586 nm（⁵D₀→⁷F₁）of Li Sr B₉O₁₅:x Eu³⁺（x=0.02～0.57）phosphors were compared,and the occupation of Eu³⁺in the Li Sr B₉O₁₅matrix lattice was discussed.The luminescence properties of the prepared Li Sr B₉O₁₅:0.52Eu³⁺and the commercial Y₂O₃:Eu³⁺was compared.The emission intensity of Li Sr B₉O₁₅:0.52Eu³⁺is weaker than the Y₂O₃:Eu³⁺under excitation of 260 nm wavelength,stronger than that of the Y₂O₃:Eu³⁺under excitation of 362 nm and 394 nm wavelength.The effect of Gd³⁺doping on the luminescence properties of LiBaB₉O₁₅:0.07Eu³⁺and Li Sr B₉O₁₅:0.07Eu³⁺phosphor was investigated.Gd³⁺and Zn²⁺doped LiBa（Sr）B₉O₁₅:0.07Eu³⁺phosphors were synthesized by the cation substitution method,the effect of different Gd³⁺and Zn²⁺doping amount on the luminescence properties was studied.The results show that the doping of appropriate amounts of Gd³⁺and Zn²⁺has no effect on the peak shape and peak position of the phosphor,but can increase the luminescence intensity of samples.